Microtransducers made of conductive silicone rubber (Silastic) will be used to characterize cervical muscular activity in the unanesthetized, unrestrained female baboon. The use of multiple transducers in the cervix that detect constriction, and dilation of the cervical muscle wall permits transegmental comparison of cervical activity. A micro-power telemetry system will permit long-term continuous recordings of cervical activity. The system will be used to measure daily changes in contractile activity throughout the menstrual cycle. Changes in activity will be correlated with corresponding changes in plasma levels of estradiol and progesterone as measured by radioimmnoassay. Recordings made during coitus will determine what effect mating and the presence of semen in the vagina have on cervical activity. Pharmacological experiments will be performed to determine the effects of prostaglandin (E and F), oxytocin, and epinephrine on cervical activity.